1. Field of the Invention
This invention relates to a timer device for an electric rice cooker or like cooking apparatus by which applying heat to rice or other foodstuff is automatically started after lapse of a period of time set, and more particularly to such a device which is capable of selectively setting either the cooking completion time and the current time or the cooking completion standby period of time.
2. Description of the Prior Art
In an electric rice cooker which employs the cooking control circuitry comprised of a microcomputer, for example, the cooking operation is completed under timer control after lapse of a desired period of time by using a timing function given to the microcomputer. This cooking operation is so called "timer-controlled cooking operation." This type of rice cooker has a switch for setting a standby period of time, and the cooking operation is started after lapse of the standby period of time set. The operator must, however, calculate the cooking start time which value is obtained by subtracting the value of a cooking period of time from the value of desired cooking completion time. Further, the operator must calculate the standby period of time which value is obtained by subtracting the value of the current time from the value of the cooking start time and set the standby period of time in the timer device. This setting mode is referred to as "standby time period set mode." Thus the prior art rice cooker forces the operator into troublesome calculation in setting the standby period of time.
In order to overcome defects of the prior art rice cooker described above, the inventors have contemplated that a necessary standby period of time is calculated in the microcomputer when the operator inputs a current time data and a desired cooking completion time data, the cooking operation being started after lapse of the standby time period. This setting mode is referred to as "time set mode." For example, when the operator sets the timer to cook rice for the next morning meal before sleeping at night in accordance with the standby time period set mode, he or she is forced into complicated duodecimal calculation. According to the time set mode, what is required of the operator is to set the current time and the desired cooking completion time. However, when the operator sets the timer in the afternoon to cook rice for the evening meal at about seven o'clock, he or she would rather mentally calculate the difference value between the desired cooking completion time and the current time to set in the timer according to the standby time period set mode than set the current time and the cooking completion time. That is, even when the operator can easily find the difference value between the desired cooking completion time and the current time, the operator is forced to set the current time and the cooking completion time one by one in accordance with the time set mode.